Effects of Noise Bandwidth and Amplitude Modulation on Masking in Frog Auditory Midbrain Neurons

Natural auditory scenes such as frog choruses consist of multiple sound sources (i.e., individual vocalizing males) producing sounds that overlap extensively in time and spectrum, often in the presence of other biotic and abiotic background noise. Detection of a signal in such environments is challenging, but it is facilitated when the noise shares common amplitude modulations across a wide frequency range, due to a phenomenon called comodulation masking release (CMR). Here, we examined how properties of the background noise, such as its bandwidth and amplitude modulation, influence the detection threshold of a target sound (pulsed amplitude modulated tones) by single neurons in the frog auditory midbrain. We found that for both modulated and unmodulated masking noise, masking was generally stronger with increasing bandwidth, but it was weakened for the widest bandwidths. Masking was less for modulated noise than for unmodulated noise for all bandwidths. However, responses were heterogeneous, and only for a subpopulation of neurons the detection of the probe was facilitated when the bandwidth of the modulated masker was increased beyond a certain bandwidth – such neurons might contribute to CMR. We observed evidence that suggests that the dips in the noise amplitude are exploited by TS neurons, and observed strong responses to target signals occurring during such dips. However, the interactions between the probe and masker responses were nonlinear, and other mechanisms, e.g., selective suppression of the response to the noise, may also be involved in the masking release

The education utility : the power to revitalize education and society /

Bibliogr.: p. 185-186Comprend des inde

New directions for continuing education

Publ. comme no 34, summer 1987 de la revue New directions for continuing educationBibliogr. à la fin des textesIndex: p. 109-11

Theory-driven evaluation of the Work and Health Initiative: A Focus on Winning New Jobs

The mission of the Work and Health Initiative funded by The California Wellness Foundation (TCWF) was to improve the health of Californians by funding employment-related interventions. Fundamental to this Initiative was the perspective that important relationships between work and health are shaped by an evolving California economy. The goals of the Initiative were to (1) understand the rapidly changing nature of work and its effects on the health of Californians; (2) increase access to high quality employment for all Californians; (3) improve conditions of work for employed Californians; and (4) expand the availability of worksite health programs and benefits